Efficacy of Artabotrys odoratissimus oil as a plant based antimicrobial against storage fungi and aflatoxin B1 secretion

The essential oil of Artabotrys odoratissimus R.Br. was evaluated for antifungal activity against some storage fungi causing contamination of food stuffs. Minimum inhibitory concentration of the oil was found to be 750 μL L⁻¹ against Aspergillus flavus Link. It was found superior over different prevalent synthetic fungicides which inhibited the growth of A. flavus between 1000–5000 μL L⁻¹. The oil exhibited broad fungitoxic spectrum against fourteen different storage fungi. Aspergillus fumigatus was inhibited at 1000 μL L⁻¹ whereas Cladosporium cladosporioides , Curvularia lunata , Fusarium oxysporum , Helminthosporium oryzae , Macrophomina phaseolina , Microsporum gypseum , Mucor racemosus , Penicillium italicum , Pythium debaryanum , Rhizoctonia solani , Sclerotium rolfsii and Trichoderma viride at 500 μL L⁻¹. Aspergillus niger was found to be inhibited only 84.9% at 1000 μL L⁻¹. In addition, the oil showed significant efficacy in arresting aflatoxin B₁ secretion by the toxigenic strain (Navjot 4NSt) of A. flavus at 750 μL L⁻¹. The efficacy of A. odoratissimus oil as aflatoxin suppressor is being reported for the first time.     

Efficacy of extract and essential oil of Lantana indica Roxb. against food contaminating moulds and aflatoxin B1 production

The study investigates the antifungal and antiaflatoxigenic efficacy of Lantana indica against Aspergillus flavus , a key storage fungus. The leaf essential oil of L. indica was found more active than leaf extracts. The oil absolutely inhibited the growth of A. flavus at 1.5 mg mL⁻¹ while ethanolic and chloroform extracts of leaf show MIC at 7.5 and 10.0 mg mL⁻¹ concentrations respectively. The oil also showed pronounced antiaflatoxigenic efficacy and completely inhibited the aflatoxin B₁ production at 0.75 mg mL⁻¹. The ethanolic and chloroformic extracts inhibited the aflatoxin B₁ production at 5.0 and 7.5 mg mL⁻¹, respectively while other extracts exhibited poor efficacy. The L. indica essential oil exhibited broad fungitoxic spectrum against twelve different storage moulds. The present findings may recommend the L. indica essential oil and its bioactive leaf extracts as natural preservative would of immense significance in view of the environmental and toxicological implications by indiscriminate use of synthetic pesticides .     

COMBINED EFFECT OF pH AND HEAT TREATMENT ON DEGRADATION OF AFLATOXINS IN DRIED FIGS

Dried figs are sensitive commodities to aflatoxin contamination. Although preventive methods are the logical solution to aflatoxin problems, once the product is contaminated, decontamination procedures are inevitable. In this study, the effectiveness of a procedure consisted of acidification/alkalization, and heat treatment in degradation of aflatoxins was evaluated. The pH of dried fig extracts was adjusted to 3.1, 3.5, 6, 8 or 10 by adding acid or base. Extracts were heated at 50, 75 or 98C for 1 or 2 h, and then the residual aflatoxin B₁, B₂, G₁ and G₂ were determined. The highest level of degradation for aflatoxin B₁ (97  ±  1%) and B₂ (87  ±  1%) were observed at pH 10 in samples heated at 98 and 50C, respectively. Some treatments resulted in 100% degradation of aflatoxin G₁ and G₂ so that they could not be detected.

PRACTICAL APPLICATIONS

Aflatoxin contamination is a serious problem for a number of processed and non-processed foods, including dried figs. This not only presents severe risks to human and animal health but also causes economic problems for countries such as Turkey, U.S.A., Greece and Spain, which produce and export dried figs. It is clear that detoxifying studies are unavoidable when the amount of crop contaminated by toxins is considered. Therefore, the food industry is in search of applications that are effective in mycotoxin detoxification and adaptable to food processes. This is the first report on degradation of aflatoxins in naturally contaminated dried figs by such a promising method.     

Aflatoxin levels in dried figs, nuts and paprika for export from Turkey

Three hundred and thirteen of 2643 dried fig, two of eighty hazelnut, sixteen of twenty-eight pistachio, five of ten peanut and nineteen of twenty-three paprika samples for export from Turkey were contaminated with total aflatoxins in the range of 0.2–162.76, 5.46–6.55, 2.31–63.11, 0.75–26.36 and 1.79–6.55 μg kg⁻¹, respectively. Samples were collected from January to August 2007 and tested for aflatoxins (B₁, B₂, G₁ and G₂) by immunoaffinity column extraction using RP-HPLC. Fifty-six of the 313 dried fig, all of the contaminated hazelnut and pistachio, two of the sixteen peanut and three of the nineteen paprika samples exceeded the regulatory limits of the European Union. The ratio of the different types of aflatoxin present in each sample exhibited great variability. For example, of 313 contaminated fig samples, 159 contained only aflatoxin B₁, eighty-five contained B₁ (49.7%) + G₁ (50.3%), twenty-two contained only G₁, twenty contained B₁ (89.4%) + B₂ (10.6%), thirteen contained B₁ (73.7%) + B₂ (10.8%) + G₁ (15.5%) and fourteen contained all four types, B₁ (26%) + B₂ (2.5%) + G₁ (66.5%) + G₂ (5%).     

SYNERGISTIC EFFECT OF VITAMIN B1 ON SANITIZER AND DISINFECTANT TREATMENTS FOR REDUCTION OF BACILLUS CEREUS IN RICE

The synergistic bactericidal effects of vitamin B₁ (thiamine dilauryl sulfate) and the efficacy of commercial sanitizers for minimization of Bacillus cereus contamination in cooked rice were investigated. Sanitizer-treated rice exhibited a greater reduction than water-treated rice, while sanitizer-treated rice with Vitamin B₁ produced an even greater reduction. The treatments for B. cereus in rice included (1) 100 ppm hydrogen peroxide with 500 ppm vitamin B₁; (2) 200 ppm hydrogen peroxide with 100 ppm vitamin B₁; (3) 400 ppm hydrogen peroxide; (4) 50 ppm chlorine with 500 ppm vitamin B₁; (5) 60 ppm chlorine with 300 ppm vitamin B₁; (6) 70 ppm chlorine with 100 ppm vitamin B₁; (7) 80 ppm chlorine; and (8) 100,000 ppm ethanol with 500 vitamin B_1. All treatments completely eliminated B. cereus in rice. The sensory properties of all sanitizer-treated cooked rice did not differ significantly from the same properties for water-treated cooked rice.

PRACTICAL APPLICATIONS

The prevalence of Bacillus cereus in rice and rice products has been documented and control of the growth of B. cereus in rice is an important consideration. The results obtained from this study can be of use to rice producers in the manufacture of safe products. Although chemical disinfectants can be used to reduce the amount of B. cereus in rice, vitamin B₁ can also be used as an effective additive that reduces the amount of disinfectant use via a synergistic antimicrobial effect. The increasing use of chemical disinfectants for safety in the food industry can be reversed using our method.     

Aflatoxin Removal from Pistachio Nuts by Natural Natrolite

ABSTRACT: Natrolite was used to explore a physical and safe method to decontaminate aflatoxin-containing pistachio lots. Pistachio nuts with low, medium, and high levels of aflatoxin were subjected to a washing process with a slurry of 5% natrolite. Using thin-layer chromatography and scanning, the aflatoxin contents of the samples were measured. Aflatoxins B₁ and B₂ were found in pistachio nuts. The majority of total aflatoxins was aflatoxin B₁ Natrolite treatment resulted in a 38% to 100% reduction in aflatoxin B₁, depending on the initial aflatoxin level. Although natrolite was demonstrated to be an effective candidate to reduce aflatoxin B₁, its efficacy against aflatoxin B₂ was limited.     

Natural maize phenolic acids for control of aflatoxigenic fungi on maize

ABSTRACT:  Natural phytochemicals may be an alternative to synthetic chemicals for controlling fungal growth and mycotoxin production in stored maize. A key to progress in this field is to select the best natural maize phytochemicals to be applied in a storage maize ecosystem. This research was undertaken to evaluate the effects of the natural phytochemicals trans-cinnamic acid (CA) and ferulic acid (FA) alone at concentrations of 20 to 30 mM and in 5 combinations on Aspergillus flavus Link and A. parasiticus Speare populations and aflatoxin B₁ production. Studies on Aspergillus population and aflatoxin B₁ production were carried out in maize grain in relation to a water activity a_w of 0.99, 0.97, 0.95, and 0.93. CA and FA at concentrations of 25 to 30 mM, respectively, and CA-FA mixture T9 (25 + 30 mM) were the treatments most effective at inhibiting A. flavus and A. parasiticus population at all a_w assayed after 11 d of incubation. At all a_w values, the mixture CA-FA T9 (25 + 30 mM) completely inhibited (100%) aflatoxin B₁ production by both strains at a_w= 0.99, 0.97, 0.95, and 0.93. Decreased aflatoxin B₁ levels in comparison with the control were observed with mixtures CA-FA T6 (10 + 25 mM), T7 (20 + 20 mM), and T8 (20 + 30 mM) of both strains in the majority of a_w assayed. The data show that CA and FA could be considered as effective fungitoxicants for A. flavus and A. parasiticus in maize in the a_w range 0.99 to 0.93. The information obtained shows promise for controlling aflatoxigenic fungi in stored maize.     

Aflatoxin Inactivation Using Aqueous Extract of Ajowan (Trachyspermum ammi) Seeds

ABSTRACT: Aqueous extract of ajowan seeds was found to contain an aflatoxin inactivation factor (IF). Thin layer chromatography analysis of the toxins after treatment with IF showed relative reduction of aflatoxin G₁ > G₂ > B₁ > B₂. Quantification of toxin using a fluorotoxin meter as well as the Enzyme Linked Immuno s orb ent Assay (ELISA) confirmed these findings. An approximate 80% reduction in total aflatoxin content over the controls was observed. This observed phenomenon of reduction in total toxin was referred to as toxin inactivation. Temperature was found to influence the rate of toxin inactivation. At 45 °C, it was found to be rapid during the initial 5 h and slowed later. The IF was found to retain considerable activity even after boiling and autoclaving, indicating partial heat stability. The activity was lost below pH 4.0. Above pH 4.0, it increased gradually, reaching the maximum at pH 10.0. IF was found to be stable to gamma irradiation. Toxin decontamination in spiked corn samples could be achieved using IF. This study emphasizes the potential of ajowan IF in aflatoxin removal from contaminated food commodities. However, the biological toxicity, if any, of the IF inactivated aflatoxins needs to be confirmed, and the work in this direction is in progress.     

EFFECT OF GAMMA IRRADIATION ON AFLATOXIN B1 PRODUCTION BY ASPERGILLUS FLAVUS IN GROUND BEEF STORED AT 5C

The effect of γ-irradiation for controlling the production of aflatoxin B₁ by Aspergillus flavus in ground beef stored at 5C for 2 weeks was investigated. Aspergillus, Penicillium, Cladosporium, Mucor, Scopulariopsis, Candida and Rhodotorula were the most common fungal genera contaminating ground beef. A. flavus and A. niger were the most common Aspergillus spp. Aspergillus flavus isolates were able to produce aflatoxin B₁ in ground beef. Only 3 (20%) samples of ground beef were contaminated with aflatoxin B₁ (25–45 μg/Kg). Gamma irradiation dose levels resulted in an immediate reduction in the total numbers of A. flavus. No growth or aflatoxin B₁ production occurred at 1.50 kGy during storage.     

RESEARCH NOTE: MYCOTOXINS IN FENNEL SEED

Ten samples of fennel seed from fields in India were examined for the presence ofaflatoxins B₁, B₂, G₁ and G₂. Five of the samples were fluorescent or became fluorescent during a 12 month storage period. Only aflatoxins B₁, B₂ and G₁ were identified. One nonfluorescent sample contained detectable aflatoxin B₁ after 12 months of storage.     

INFLUENCE OF OTHER FUNGI ON AFLATOXIN PRODUCTION BY ASPERGILLUS FLAVUS IN MAIZE KERNELS

Experiments were designed to determine whether certain nontoxigenic fungi commonly isolated from maize kernels can affect aflatoxin B₁ development when inoculated with A. flavus onto individual unsterilized, and autoclaved maize kernels . Trichoderma viride and Aspergillus niger were found to be strongly antagonist inhibiting the growth of A. flavus by 87 and 66% respectively, whereas Aspergillus versicolor, Fusarium moniliforme, Paecilomyces variotii and Emericella quadrillineata inhibited the growth of A. flavus by less than 51%. Less aflatoxin B₁ was detected when A. flavus was paired with A. niger or T. viride than with the other test fungi. When A. niger or T. viride was introduced onto the kernels 72 h before inoculation with A. flavus, no aflatoxin B₁ was detected in unsterilized kernels and the levels of aflatoxin B₁ were greatly reduced from 700 ppb to 160 and 140 ppb in autoclaved kernels, respectively. When inoculation of A. flavus followed 72 h of incubation of either A. niger and T. viride, no aflatoxin B₁ was detected. However, when both A. niger and T. viride were introduced 72 h after inoculation with A. flavus, the levels of aflatoxin B₁ were reduced to 385 and 560 ppb, respectively in unsterilized and autoclaved maize kernels . Trichoderma viride and Aspergillus niger may be useful in biological control of aflatoxin contamination of maize kernels .; Accepted for Publication June 11, 1997     

INHIBITION OF ASPERGILLUS PARASITICUS GROWTH AND TOXIN PRODUCTION BY GARLIC

Mycelial growth and toxin production by Asperigillus parasiticus were inhibited by garlic concentrations of 0.3–0.4%. When the fungus was grown in broth, aflatoxin B₁ production was inhibited at a garlic concentration of 0.3% while aflatoxin G₁ production was inhibited by 0.25% garlic. When growth on rice, aflatoxin B₁ was detected at garlic concentrations of up to 2.5%. Aflatoxin G₁ was detected at 1.25% garlic concentration but not above this level.     

A SIMPLE SOLID-PHASE RADIOIMMUNOASSAY FOR AFLATOXIN B1

A solid-phase radioimmunoassay (RIA) for aflatoxin B₁ (afla B₁) was developed. This method involved the incubation of afla B₁, both labelled and unlabelled, with immunoglobulin (IgG)-sepharose gel which was prepared by conjugation of the IgG highly specific to afla B₁ with CNBr-activated sepharose gel, followed by a filtration step. The binding capacity was determined by counting the radioactivity in the filtrate. Studies with different afla B₁ analogues revealed that the IgG-gel bound most effectively with B₁. Binding of afla B₂, G₁, G₂, and aflatoxicol to the IgG-gel was less effective in comparison with the IgG before coupling. Between 0.5–5.0 ng per assay, the displacement of radioactivity from the gel was directly proportional to the amount of afla B₁ present. Using a simple extraction procedure without clean-up step, the recovery yields for afla B₁ in the contaminated corn or wheat at levels of 5 ppb or above were above 60%.     

Effect of Salt, Smoke Compound, and Temperature on the Survival of Listeria monocytogenes in Salmon during Simulated Smoking Processes

ABSTRACT:  The objectives of this study were to examine and develop a model to describe the survival of  Listeria monocytogenes  in salmon as affected by salt, smoke compound (phenol), and smoking process temperature. Cooked minced salmon containing selected levels of salt (0%, 2%, 4%, and 6%) and smoke compound (0, 5, 10, and 15 ppm phenol) were inoculated with a 6-strain mixture of  L. monocytogenes  to an inoculum level of 6.0 log₁₀ CFU/g. The populations of  L. monocytogenes  in salmon during processing at 40, 45, 50, and 55 °C that simulated cold- and hot-smoking process temperatures were determined, and the effects of salt, phenol, and temperature on the survival of  L. monocytogenes  in salmon were analyzed and described with an exponential regression. At 40 °C, the populations of  L. monocytogenes  in salmon decreased slightly with inactivation rates of <0.01 log₁₀ CFU/h, and at 45, 50, and 55 °C, the inactivation rates were 0.01 to 0.03, 0.15 to 0.30, and 2.8 to 3.5 log₁₀ CFU/h, respectively. An exponential regression model was developed and was shown to closely describe the inactivation rates of  L. monocytogenes  as affected by the individual and combined effects of salt, phenol, and smoking process temperature. Temperature was the main effector in inactivating  L. monocytogenes  while salt and phenol contributed additional inactivation effects. This study demonstrated the inactivation effects of salt, smoke compound, and temperature on  L. monocytogenes  in salmon under a smoking process. The data and model can be used by manufacturers of smoked seafood to select concentrations of salt and smoke compound and alternative smoking process temperatures at 40 to 55 °C to minimize the presence of  L. monocytogenes  in smoked seafood.     

Aflatoxins in imported edible nuts: some data 1982–84

Results of 188 analyses for aflatoxin in edible nuts imported into the U.K. during 1982–84 are presented. Most samples (140/188, 74%) had aflatoxin B₁, content ≤ 5 μg/kg. Brazilian peanuts may be identified as consistently unreliable as regards aflatoxin contamination.     

Assessment of Pelargonium graveolens oil as plant‐based antimicrobial and aflatoxin suppressor in food preservation

BACKGROUND: Contamination of stored food commodities by moulds and mycotoxins results in qualitative as well as quantitative losses. Most of the synthetic antimicrobials used for preservation of stored food items produce side effects in the form of residual and mammalian toxicity. Recently some higher plant products have been recommended as safe alternatives of such synthetic antimicrobials. In the present investigation antifungal efficacy of some essential oils was evaluated against two toxigenic strains of Aspergillus flavus with special reference to the oil of Pelargonium graveolens to investigate its potential to inhibit aflatoxin B₁ secretion. RESULTS: Essential oil of P. graveolens exhibited absolute fungitoxicity against both the toxigenic strains of A. flavus. The minimum inhibitory concentration of the oil was found to be 0.75 g L^?1 and exhibited a fungistatic nature. It was found superior over the synthetic fungicides tested and exhibited a broad fungitoxic spectrum. The oil showed excellent anti‐aflatoxigenic efficacy as it completely inhibited aflatoxin B₁ production even at 0.50 g L^?1. CONCLUSION: This is the first report on the aflatoxin B₁ inhibitory nature of P. graveolens oil. It may be recommended as a novel plant‐based antimicrobial as well as aflatoxin B₁ suppressor over synthetic preservatives in food protection. Copyright © 2008 Society of Chemical Industry     

AFLATOXIN PRODUCTION ON TWO MUSHROOM SUBSTRATES

Two fungi, Boletus edulis and Agaricus bisporus, were tested as substrates for two known aflatoxigenic fungi, Aspergillus flavus ATCC 15548 and A. parasiticus NRRL 2999. Both autoclaved substrates supported mycelial growth, sporulation, and aflatoxin production; however, the B. edulis substrate allowed more rapid mold growth and greater toxin production than did the A. bisporus substrate under laboratory conditions. Both aflatoxins B₁ and AFG₁ were produced with AFG₁ being the predominant toxin. Aflatoxins B₂ and AFG₂ were not detected. Although toxin was produced at low levels, the highest mean being 0.55 μg/g substrate for AFB₁ and AFG₁, both mushrooms apparently contained minimal nutrients for toxigenic mold growth and failed to cause antimycotic or antiaflatoxigenic responses. Routinely used aflatoxin extraction and analytical procedures appear applicable for such testing of mushrooms.     

PREPARATION AND CHARACTERIZATION OF AFLATOXIN B2a-HEMIGLUTARATE AND ITS USE FOR THE PRODUCTION OF ANTIBODY AGAINST AFLATOXIN B1

Hemisuccinate (HS) and hemiglutarate (HG) of aflatoxin B_2a (afla B_2a) were prepared by refluxing afla B_2a with the corresponding anhydride and 4-N, N-dimethylaminopyridine in tetrahydrofuran. Two epimers of the respective HS or HG which show different chromatographic behavior and physiochemical properties were isolated and characterized. Afla B_2a-HS hydrolyzes very rapidly in aqueous solution and was not used for further study. Afla B_2a-HG hydrolyzes at a much slower rate and was selected for the coupling to protein. Using the mixed anhydride method, as much as 12 moles of afla B_2a-HG were conjugated to each mole of bovine serum albumin (BSA). The antibody obtained from rabbits immunized with afla B_2a-HG BSA is most specific to afla B₁ and shows little cross reaction with afla G₁ and aflatoxicol. The lower limit for detection of afla B₁ by radioimmunoassay using this antibody is in the range of 30–50 pg per assay.     

EVALUATION OF AMOMUM SUBULATUM ROXB OIL AS A SOURCE OF BOTANICAL FUNGITOXICANT FOR THE PROTECTION OF MANGO FRUITS FROM FUNGAL ROTTING

The essential oil extracted from the leaves of Amomum subulatum Roxb. (Zingiberaceae) has been evaluated for efficacy in the control of mango fruit rotting due to fungal infections. The essential oil of A. subulatum exhibited absolute antifungal activity against two mango rotting fungi viz. Botryodiplodia theobromae Pat. and Colletotrichum gloeosporioides Penz, the common storage fungi causing stem end rot and anthracnose disease of mango fruits. The oil showed its absolute fungitoxicity at the minimum inhibitory concentration of 500 µL/L. Its fungitoxic potency did not alter even on a high inoculum density of the test fungi. The Amomum oil significantly enhanced the shelf life of mango fruits by controlling anthracnose disease as well as stem end rot for an additional five and six days, respectively. The oil also inhibited pectinase and cellulase enzymes secreted by the test fungi during pathogenesis and exhibited a wide range of fungitoxicity against 13 fungal isolates. Gas chromatography-mass spectrometry analysis of the oil found 1, 8 cineole to be a major component. The LD₅₀ of Amomum oil was found to be 22,070 mg/kg of body weight in mice ( Mus musculus L.) when administered for acute oral toxicity. Keeping in view the side effects of synthetic fungicides, A. subulatum oil may be recommended as a botanical fungitoxicant of plant origin to control the rotting of mango fruits and to enhance their shelf life because of its nonmammalian toxicity and in vivo efficacy.     

Chemical Composition and Antimicrobial and Antioxidant Activities of Mentha (longifolia L. and viridis) Essential Oils

ABSTRACT:  The study was aimed to investigate essential oil chemical composition (gas chromatography/flame ionization detection [GC-FID] and gas chromatography/mass spectrometry [GC-MS]) and antioxidant (1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate [ABTS] assays) and antimicrobial (Gram-positive and Gram-negative bacteria, fungi, and yeast) activities of essential oils extracted from leaves of  Mentha longifolia  L. and  Mentha viridis . GC-MS analysis revealed that  M. longifolia  was constituted by pulegone (54.41%) as a major component followed by isomenthone (12.02%), 1,8-cineole (7.41%), borneol (6.85%), and piperitenone oxide (3.19%).  M. viridis  was rich in carvone (50.47%), 1,8-cineole (9.14%), and limonene (4.87%). The antioxidant activity by ABTS assay showed  IC ₅₀ values of 476.3 ± 11.7 and 195.1 ± 4.2 mg/L for  M .  longifolia  and  M .  viridis , respectively, the DPPH assays have resulted in a moderate  IC ₅₀ (>8000 mg/L and 3476.3 ± 133 mg/L for  M .  longifolia  and  M .  viridis , respectively). Antimicrobial activity showed that  Listeria monocytogenes  and  Klebsiella pneumoniae  bacteria were more inhibited by the 2 essential oils tested.  Escherichia coli  was least susceptible. A strong activity was also observed on fungi and yeasts. Carvone, thymol, and piperitone oxide have not been detected in Tunisian  M. longifolia . Camphor is reported for the 1st time for  M. viridis . Antioxidant and antibacterial activities were correlated to chemical composition.